The present invention relates to alloys comprising, in addition to at least one heavy element from column III of Mendeleev's periodic table and specifically indium or thallium, at least two elements from group V usable on a monocrystalline substrate, and a generally binary compound of elements from groups III and V to constitute an infrared emission transducer such as a light-emitting diode, or an infrared detector such as a photodiode.
Numerous composite semiconductors have already been proposed for infrared detection. A widely-used material is (Cd, Hg)Te deposited by epitaxial crystal growth on a monocrystalline substrate of (Cd Te) or of (Cd, Zn)Te. These combinations of elements from groups II and VI of the periodic classification suffer from various drawbacks. Their forbidden bands vary very quickly with alloy composition so that it is difficult to make matrices having a large number of pixels that all have the same cutoff wavelength; the crystal lattice has numerous defects, in particular in thermal infrared detectors, thereby generating noise.
Proposals have also been made for various components that associate elements from groups III and V, and in particular:
(In.sub.1-x Tl.sub.x) P on an Inp substrate; PA1 (In.sub.1-x Tl.sub.x) As on an InAs substrate; PA1 (In.sub.1-x Tl.sub.x) Sb on an InSb substrate; and PA1 (In.sub.1-x Tl.sub.x) (As.sub.1-y P.sub.y) on an InP substrate.
It is also known that most transducers are designed to operate in the 3 micron (.mu.m) to 5 .mu.m range (mid infrared) or in the 8 .mu.m to 12 .mu.m range (thermal infrared). The above compounds, described in document WO 96/05621 to which reference can be made, do not make it possible simultaneously and to a sufficient extent, to fulfill both of the conditions that are necessary for making transducers with a large number of pixels, i.e. the ability to adapt cutoff wavelengths merely by changing the proportions of the components, and having very few lattice defects when they are made by epitaxial growth on an appropriate substrate.